CN114157385B - Anti-interference method of network - Google Patents
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- CN114157385B CN114157385B CN202111402640.1A CN202111402640A CN114157385B CN 114157385 B CN114157385 B CN 114157385B CN 202111402640 A CN202111402640 A CN 202111402640A CN 114157385 B CN114157385 B CN 114157385B
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Abstract
The invention provides an anti-interference method of a network, which is applied to a first node of the network, wherein the method comprises the following steps: after data transmission is carried out on a first channel on a link formed by a first node and a second node in the network, whether interference exists on the link is judged according to data information, and the data information is obtained after the data transmission is carried out on the first node and the second node; and when the link has interference, the data transmission is carried out again. The method is used for solving the defect that extra energy consumption is needed in the anti-interference processing of the network in the prior art, and sensing and processing the interference on the link are realized on the basis that extra energy is not consumed in the IEEE802.15.4e network.
Description
Technical Field
The invention relates to the technical field of network anti-interference, in particular to an anti-interference method of a network.
Background
Time Slot Channel Hopping (TSCH) defined in the IEEE802.15.4e standard is a TDMA-based MAC protocol, which, in combination with channel hopping, meets the requirements of key applications such as the industrial internet of things. The standard does not specify how the TSCH scheduling protocol allocates time slots and channels to individual links, but leaves this problem to the system designer.
However, time slot and channel scheduling under interference by TSCH still faces unique challenges: on the one hand, it is necessary to maximize the success rate of packet delivery in order to achieve reliable communication performance, and on the other hand, the transmission overhead of constructing and maintaining the schedule should be minimized to maximize the network lifetime.
It is well known that interference can severely impact network performance because it can cause transmission failures between nodes and additional energy consumption due to retransmissions. Meanwhile, the interference may be internal, i.e. caused by other sensor nodes operating in the same ieee802.15.4 network, or external, i.e. caused by nearby wireless devices using other radio technologies of the same frequency. Therefore, robustness of communication to interference is an important consideration when designing scheduling protocols.
However, existing scheduling protocols either maintain information about interference at extra cost or fix the scheduling rules in case the interference is unpredictable. None of these scheduling protocols enable interference awareness. In addition, in order to minimize interference, the centralized scheduling protocol either first needs to obtain a global view of interference at the coordinating node, while the distributed scheduling protocol first needs to obtain a global view of interference at the coordinating node, or first needs to obtain a local image of interference at each node, and then adjust the time slots or channels accordingly, which undoubtedly requires additional control traffic, i.e., increases the energy consumption of the nodes, thereby offsetting the benefits introduced for mitigating interference.
Disclosure of Invention
The invention provides an anti-interference method of a network, which is used for solving the defect that extra energy consumption is needed in the anti-interference processing of an IEEE802.15.4e network in the prior art and realizing the sensing and processing of the interference on a link on the basis of not consuming extra energy in the IEEE802.15.4e network.
The invention also provides an anti-interference method of the network, which is applied to the first node of the network and comprises the following steps:
after data transmission is carried out on a first channel on a link formed by a first node and a second node in the network, whether interference exists on the link is judged according to data information, and the data information is obtained after the data transmission is carried out on the first node and the second node;
and when the link has interference, the data transmission is carried out again.
According to the anti-interference method of the network, the data information comprises a data packet received by the first node;
the determining whether there is interference on the link according to the data information specifically includes:
judging whether the received data packet is a correct data packet from the second node on the link or not;
determining that interference exists on the link in response to the received data packet not being the correct data packet.
According to the method for resisting interference of a network, the determining whether the received data packet is a correct data packet from the second node on the link includes:
determining that the received data packet is not the correct data packet in response to the received data packet satisfying at least one condition of a preset set of conditions;
wherein the preset condition set comprises the following conditions:
the received data packet is a data packet of other links in the network;
the data packets received in two adjacent time slots are the same data packet;
the received data packet is an invalid data packet which cannot be analyzed, and the average value of all received signal intensities collected in a preset time length exceeds a preset intensity threshold value.
According to the anti-interference method for the network, when the link has interference, the data transmission is resumed, specifically including:
re-transmitting the data using a second channel of the link; the second channel is a spare channel of the first channel.
According to the interference rejection method for the network of the present invention, before data transmission is performed based on a first channel on a link formed by a first node and a second node in the network, the method further includes:
determining a time slot, a first channel and a second channel for the data transmission;
wherein the time slot, the first channel, and the second channel are determined based on an autonomous scheduling protocol.
According to the interference rejection method for the network of the present invention, when there is interference in the link, the data transmission is resumed, further comprising:
performing weighted calculation according to the estimated probability of the link interference occurring in the last time slot to obtain the estimated probability of the link interference occurring in the current time slot;
determining the interference strength of the link when the interference occurs according to whether the estimated probability of the current time slot exceeds the preset probability;
when the interference strength exceeds a predefined threshold, the data transmission is carried out again on the second channel, and the identification information of the preset strategy for processing the existing interference is transmitted while the data transmission is carried out, so that the second node processes the existing interference together with the first node according to the preset strategy identified by the identification information of the preset strategy;
wherein an initial value of the estimated probability is set based on a traffic load of the network.
According to the anti-interference method for the network of the present invention, the transmitting the identification information of the preset strategy for processing the existing interference while the data transmission is performed includes:
and carrying the identification information of the preset strategy in a response data packet sent to the second node, wherein the response data packet represents that the first node successfully receives the data packet sent by the second node.
According to the anti-interference method of the network of the present invention, before transmitting the identification information of the preset policy for processing the existing interference while performing the data transmission, the method further includes:
determining a type of the interference present;
and determining the identification information of the preset strategy corresponding to the existing interference based on the corresponding relation between the type of the interference and the identification information of the preset strategy.
According to the anti-interference method of the network, when the type of the existing interference is internal interference, the preset strategy comprises the following steps: the data transmission is carried out again on the second channel, and the time slot for carrying out the data transmission on the first channel is mapped to a new time slot;
when the type of the existing interference is external interference, the preset strategy comprises: and the data transmission is carried out again on the second channel, and the first channel used for the data transmission in the current time slot is listed in a channel blacklist of the link.
The invention also provides an electronic device comprising a memory, a processor and a computer program stored on the memory and operable on the processor, wherein the processor implements the steps of the interference rejection method of any one of the networks when executing the program.
According to the anti-interference method of the network, whether interference exists on a link formed by a first node and a second node is judged according to data information obtained after the first node and the second node in the network carry out data transmission, and finally when the interference exists on the link, the data transmission is carried out again, so that the nodes in the network can deduce the interference by passively observing the existing data transmission, and the use of extra control flow is avoided.
Drawings
In order to more clearly illustrate the technical solutions of the present invention or the prior art, the drawings needed for the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.
FIG. 1 is a TSCH network topology;
fig. 2 is an allocation map of individual link timeslots and channels in a slotframe based on the TSCH network topology of fig. 1;
FIG. 3 is a flow chart of an anti-interference method for a network according to the present invention;
FIG. 4 is a state diagram of a node provided by the present invention in the absence of data transmission between a first node and a second node;
FIG. 5 is a state diagram of a node in the case of data transmission between a first node and a second node as provided by the present invention;
fig. 6 is a logic diagram of the first node and the second node for determining whether there is interference in the link according to the present invention;
fig. 7 is a schematic diagram illustrating an interference handling policy implemented by a first node sending an ACK packet to a second node by adjusting a time for sending the ACK packet according to the present invention;
fig. 8 is a schematic structural diagram of an electronic device provided in the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Before describing the anti-interference method of a network in detail, the related prior art is first explained:
time Slot Channel Hopping (TSCH) is a link layer protocol defined in the ieee802.15.4e standard that exploits diversity in time and frequency to improve reliability and throughput of wireless sensor networks.
In IEEE802.15.4 networks employing TSCH, low power nodes form a globally synchronized mesh network. Time is cut into time periods, typically 10ms long, sufficient for each link to complete the transmission of a data packet with an acknowledgement. The slots are grouped into slot frames, where a slotframe is a two-dimensional time-frequency schedule that indicates how each link in the network transmits or receives information using a given slot and channel combination. For simplicity, in the following description, the slot and channel combination is referred to as a trellis. For a TSCH network topology as shown in fig. 1, an example of a slotted frame for a simple network using TSCH is shown, which is a 24 grid consisting of 6 slots (0-5) and 4 channels (0-3) combined as shown in fig. 2. The slotframe iterates in the time domain, with each link being assigned a grid indicating when to transmit/receive and which channel to use.
Wherein internal interference is an inherent problem of TSCH networks. In each slotframe, links using the same mesh will suffer from internal interference if they are close enough to each other. In fig. 2, links E → B and C → a both use the grid of slot 3 and channel 3. Here, the mesh in which at least two links are allocated is named a shared mesh, so when nodes of the links in the shared mesh are assumed to be within communication range of each other, they may face packet collisions when transmitting data, which may result in complete loss of information at all nodes, or only at certain nodes, for example when a capture effect occurs, stronger signals may be successfully resolved. Therefore, to handle internal interference, the scheduling protocol needs to carefully schedule the allocation of the grid in slotframes to the various links in the network. However, although the ieee802.15.4e standard provides a back-off mechanism for nodes that can retransmit after a random number of slotted frames after a data packet loss, links in a shared grid still face higher packet loss rates under high traffic load because they compete for channel resources of the same grid.
External interference comes from transmissions from co-located wireless devices (e.g., wi-Fi devices) that do not belong to the ieee802.15.4e network, but operate on the same frequency. In fig. 2, external interference is present in channel 1. In this slotframe, it is assumed that links a → C, B → a, and B → D in the grid may be subject to external interference in the interfered channel. At this time, the TSCH uses channel hopping to handle external interference, i.e., selects different frequencies over time. While this process can eventually free the two nodes from interference and successfully exchange data, it comes at the cost of a longer delay in "blind" frequency hopping.
In summary, although various TSCH scheduling schemes have been proposed so far, there is still no effective method for handling interference, and whether the interference is internal or external, the communication performance is seriously affected.
It should be noted that the existing data transmission between nodes in the TSCH network already provides enough clues that the nodes can accumulate and use to understand the interference as a basis for subsequent reactions to the interference.
Based on the method, the invention provides an anti-interference method of the network. The interference rejection method of a network according to the present invention is described below with reference to fig. 3 to 7, and is applied to a first node of the network, and as shown in fig. 3, the method includes the following steps:
301. after data transmission is carried out on the basis of a first channel on a link formed by a first node and a second node in the network, whether interference exists on the link is judged according to data information.
302. And when the link has interference, the data transmission is carried out again.
It should be noted that, as described above, when a node performs data transmission, data information recorded by the node itself contains many clues that can be used for determining whether there is interference in a link, so that when the interference existing in the link can be analyzed through the data information recorded by the node itself, that is, the node in the network has the capability of effectively determining the interference using locally available information, and thus, on the basis of not increasing energy consumption, the node autonomously infers whether there is interference in the link, and energy consumption required in the interference rejection process is effectively reduced.
In one embodiment of the present invention, it is specifically stated that the data information includes a data packet received by the first node;
and the determining whether there is interference on the link according to the data information specifically includes:
judging whether the received data packet is a correct data packet from the second node on the link;
determining that interference is present on the link in response to the received data packet not being the correct data packet.
It should be noted that, in the ieee802.15.4e network, a first node in the same link should receive a data packet that is sent by a second node through a first channel, and after the second node sends the data packet to the first node through the first channel, the second node also receives a response data packet returned by the first node, that is, a reception result of the data packet sent by the second node by the first node, based on which, the node in the network can infer that there is interference between links in situations such as a case where the data packet received by the first node is not hi correct, that is, there is a damage or an error, or the second node does not receive the response data packet.
Therefore, each node can implicitly obtain information about the presence of interference by recording the results of ongoing transmissions over a period of time (the data information). For example, a first node may immediately notice the presence of interference, although it received a packet whose destination address is another first node. And in turn, allow each node to passively observe the interference by recording the results of each transmission.
Further, although the second node can also determine that there is interference on the link when the second node does not receive the response packet, it is fully able to infer various interference on the link only through the packet received by the first node, that is, it is inferred whether there is interference on the link through the data information of the node, and it is able to infer whether there is interference on the link based on the data information received by the first node completely, because, in the TSCH protocol, in the entire allocated time slot, the second node where no data can be sent is in a dormant state, but the first node still keeps monitoring the channel, thereby checking the existence of the packet at any time; under the condition that data communication exists between the first node and the second node, the data information received by the first node also covers the data information sent by the second node; when the first node receives an invalid data packet, the first node can also deduce whether interference exists or not based on received signal strength information (RSS) of a first channel used for data transmission in the link, which is collected by a physical layer of the network. Therefore, the first node has an advantage in inference of interference related information, and can be applied to accurate inference of whether interference exists in a link.
In another embodiment of the present invention, a method for determining whether a received data packet is a correct data packet from the second node on the link is specifically described, including:
determining that the received data packet is not the correct data packet in response to the received data packet satisfying at least one condition of a preset set of conditions;
wherein the preset condition set comprises the following conditions:
the received data packet is a data packet of other links in the network;
the data packets received in two adjacent time slots are the same data packet;
the received data packets are invalid data packets which cannot be analyzed, and the average value of all the received signal intensities collected in a preset time period exceeds a preset intensity threshold value.
It should be noted that, after data transmission, the second node and the first node can both obtain the data packet, and whether the first node and the second node can obtain the data packet depends on whether the second node communicates in the time slot to a great extent.
Specifically, as shown in fig. 4, possible states of the second node and the first node in the case where there is no data transmission between the second node and the first node are shown. The first node may obtain different states depending on the interference conditions. Specifically, the first node should detect a null channel without interference; in the presence of external interference, invalid packets that cannot be decoded should be detected, for example, by detecting high energy but failing to decode the packet; in the presence of internal interference, packets from other links, i.e. packets sent to the first node of other links, are detected.
More specifically, as shown in fig. 5, possible states of the second node and the first node in the case of data transmission between the second node and the first node are shown. Specifically, if there is no interference in the data transmission process, the first node should be able to correctly receive the data packet, and the second node also can correctly receive the corresponding ACK; if there is internal interference, the reception of the data packet may be impaired due to the transmission of data packets by other links in the same mesh. At this time, if two paths of data transmission are received by the first node with similar signal power, a collision of the first node will be caused, that is, the first node cannot decode the data packet, so the first node will not send ACK; if one of the packets is received at a higher signal power (e.g., a difference greater than the co-channel rejection ratio of the signals, typically about 3 dB), then a capture effect occurs, i.e., the first node can successfully demodulate the stronger of the two signals and receive the packet, and then depending on whether the received packet is from the intended second node, if so, the first node will not be disturbed and send an ACK back, otherwise, it will inadvertently hear the content of the packet sent to the other first node, and thus will not send any ACK; while external signal activity may occupy the first channel at any time if there is external interference, the second node may detect a busy channel when performing a CCA check before transmitting the data packet. Alternatively, the second node detects a clear channel and sends a data packet, which may not be received correctly at the first node. Therefore, the first node does not send an ACK. It is also possible that the second node sends a data packet that is also decoded correctly by its intended first node, but the ACK that the first node responds to is lost due to external interference.
Further, for the interference situation that can be inferred from the data information of the second node as mentioned above, the data packet received by the first node can also be implemented, for example, the first node can infer that the second node has not received the indication of the early ACK, that is, there is interference in the link, by the repeated data content, that is, whether the data packet containing the data content has been received before. And the first node collects the received signal strength RSS information of the first channel through a physical layer of the network in the receiving process, so that the RSS information which can be used for deducing the existence of interference is still collected when the first node fails to detect the data content, and the energy consumption caused by using the whole time slot for RSS sampling is effectively avoided.
Further, the relationship between the different second node states and whether or not there is interference in the first node state is shown in table 1 below, where "(internal interference)" indicates that there may be internal interference in addition to external interference during data transmission:
TABLE 1 relationship between different second node states and the existence of interference under the first node state
As can be seen from table 1, in actual network operation, the second node and the first node have local views only for the current state: the second/first node only solves the corresponding column/row in table 1, respectively, and does not know the state of the other. The first node is still able to deduce from the data information whether there is interference in the link.
Specifically, the following cases are included:
1. empty channel: if the first node detects an empty channel, it can unambiguously conclude that there is no interference.
2. Data packets of other links: if the first node inadvertently hears the data content contained in the data packets of the other link, it can be concluded whether there is internal interference. It will be appreciated that external interference may also affect the link in principle, since the transmitting end may CCA detect that the channel is busy, but the likelihood of this occurring is low and the first node may deduce from the analysis of the RSS samples.
3. Receiving the data packet and sending ACK: if the first node has successfully received the packet and sent a corresponding ACK, the first node can infer the state of the second node by tracking its future transmissions, i.e., if no ACK is received, the second node will resend the packet, which will result in the first node receiving a duplicate packet in the next slotted frame.
4. Signal that cannot be decoded: in the event that the first node detects an invalid signal, the first node may infer that external interference is present when the average of all collected RSS samples exceeds a preset strength threshold, typically-60 dBm, because external interference persists in the channel and is typically generated by higher power devices than IEEE802.15.4 nodes.
It can be understood that, for the data retransmission after the interference occurs, by blindly selecting another time slot, especially for the external interference suffered by the link for a long time, the probability of unsuccessful data transmission in another time slot is also great.
Based on this, in another embodiment of the present invention, when there is interference in the link, the data transmission is resumed using a second channel of the link as a backup channel of the first channel.
It should be noted that, in the anti-interference method according to the present invention, all available channels in the network are divided into a first channel and a second channel, where the first channel is used for normal communication, that is, in a normal situation, a node uses the first channel for data transmission, and the second channel is used as a backup channel and is only used for retransmission of a data packet when there is interference in a link, that is, when there is interference in the first channel, the second channel is used for data transmission again. For example, if the ZigBee node uses all available channels in 2.4GHz, i.e., channels No. 11-26, then channels 15, 20, 25, and 26 (channels that do not overlap with the main Wi-Fi channel) can be designated as second channels, and the remaining channels as first channels.
It can be understood that if the node deduces that there is no interference on the link, the second channel is not used for data transmission, which minimizes the utilization rate of the second channel, so that when there is interference on the first channel, the second channel can be used for accurate and efficient data transmission, thereby improving the robustness of the network against interference.
It will be appreciated that the autonomous scheduling protocol enables to autonomously derive time slots to be used, thereby enabling a more energy efficient scheduling, based on which the time slots, the first channel and the second channel for the data transmission are also determined based on the autonomous scheduling protocol before the data transmission is based on the first channel on the link formed by the first node and the second node in the network.
It should be noted that the first channel and the second channel are obtained by assigning all available channels in the network, and each link in the network needs to transmit or receive a data packet on an assigned channel at a given time slot, so that the time slot, the first channel and the second channel used for data transmission need to be determined before data transmission.
Specifically, before allocating time slots, a first channel and a second channel for all links based on the autonomous scheduling protocol, i.e., before initializing the scheduling of each link, the RPL protocol should also be used for initialization of all available channels and time slots and allow each node to remain linked with its parent node and all its child nodes. The transmission or reception of a packet of data by a link on an assigned channel at a given time slot is defined herein as the transmission or reception of a packet of data by a link on a given grid, while the combination of a first channel and a time slot is defined as a first grid and the combination of a second channel and a time slot is defined as a second grid.
Therefore, the grid allocation for each link follows the following formula:
TS＝mod(Hash(ID(S)+α1ID(R),SL)；
FO＝mod(Hash(α1ID(R)),ND)；
CTS＝mod(Hash(ID(S)+α2ID(R),SL)；
CFO＝mod(Hash(α2ID(R)),NC)；
wherein, TS is a time slot in the first grid; FO is the frequency offset in the first grid; CTS is a time slot in the second grid; CFO is the frequency offset in the second grid; ID (S) and ID (R) are respectively a second node address and a first node address; SL is the total number of slots in the slotframe; ND is the total number of channels in the slotframe; NC is the total number of the second channels; α 1 and α 2 are two coefficients for distinguishing the first grid from the second grid, for example: optionally, values α 1=256, α 2=255 are assigned.
It can be seen that when two links are allocated to the same first mesh, they are likely to be allocated to different second meshes, so when two links collide in the first mesh, the lost data packets can be retransmitted to different second meshes, and the internal interference in the first channel can be effectively alleviated.
After judging that the interference exists on the link according to the data information, the method further comprises the following steps:
performing weighted calculation according to the estimated probability of the link interference occurring in the last time slot to obtain the estimated probability of the link interference occurring in the current time slot;
determining the interference strength of the link when the link is interfered according to whether the estimated probability of the current time slot exceeds the preset probability;
when the interference strength exceeds a predefined threshold, the data transmission is carried out again on the second channel, and the identification information of the preset strategy for processing the existing interference is transmitted while the data transmission is carried out, so that the second node processes the existing interference together with the first node according to the preset strategy identified by the identification information of the preset strategy;
wherein an initial value of the estimated probability is set based on a traffic load of the network.
It should be noted that, whether the link has interference is determined according to whether a data packet received by a first node is a correct data packet, which may only be a real-time interference situation, and for the interference of the link, if in order to correctly react to the interference when the detected interference is relatively serious, each first node should observe the severity of the link interference for a long time, and capture the strengths of internal and external interference respectively by using estimation probabilities, that is, the first node performs weighted calculation according to the estimation probability of the link interference occurring in the previous time slot to obtain the estimation probability of the link interference occurring in the current time slot, so as to determine whether the grid frequently generates interference in a long time, specifically referring to the following formula:
wherein, P i And P i-1 The estimated probability of interference occurring in the ith time slot and the (i-1) th time slot respectively; λ is a weight coefficient and takes the value of 0<λ≤1。
As can be seen from the above equation, an Exponentially Weighted Moving Average (EWMA) is used in the calculation of the estimated probability, so that the calculation speed is fast and the stability is good, thereby effectively monitoring the quality of the first channel. Meanwhile, the value of λ directly affects the rate and stability of interference estimation, that is, the larger λ is, the higher the efficiency of interference estimation is, but the worse the stability is, and thus, in order to consider the efficiency and stability of interference estimation, the value of λ may be set based on the length of slotframe in practical application. In addition, setting the initial value of Pi based on the traffic load of the network can improve the efficiency of capturing the intensity of internal interference.
It can be understood that, since external interference may affect all nodes in the same area, in the technical solution of the above embodiment of the present invention, in order to increase the reliability in inferring whether external interference exists, a parent node having a plurality of child nodes may also be merged with the estimated probability of the plurality of child nodes.
It will be appreciated that after the second node and the first node, respectively, have inferred that interference is present, they will automatically enter the mesh in the second channel, thereby attempting a data packet retransmission. The decision logic of the second node and the first node is shown in fig. 6, that is, when the data packet is damaged by the internal interference, the second node does not receive the ACK, and the first node cannot parse the data packet during the receiving process (an invalid signal generated due to data packet collision or a data packet of another link heard due to a capturing effect). Thus, both nodes will enter the mesh in the second channel for data retransmission. Similarly, when there is external interference, the second node senses a busy channel when performing a CCA check before data transmission, or transmits a data packet without receiving an ACK. When the first node detects an invalid signal while listening to the channel for a possible data packet from the second node, both nodes will also choose to use the mesh in the second channel for data retransmission.
Therefore, when the first node is adopted to infer whether there is interference in the link in the above embodiments of the present invention, when the first node infers that there is interference, the inferred result needs to be shared with the second node with which data interaction is performed, so that a consistent reaction can be made.
Further, when it is determined that the interference strength exceeds the preset threshold, when the subsequent data is still transmitted in the current mesh, the possibility of interference occurring again is very high, and therefore, when the data transmission is performed again by using the second channel, the identification information of the preset policy for processing the existing interference is transmitted at the same time, so that the second node processes the existing interference together with the first node according to the preset policy identified by the identification information of the preset policy, that is, the first node and the second node can process the existing interference according to the preset policy.
In another embodiment of the present invention, a method for simultaneously transmitting identification information of a preset policy for processing the existing interference when data transmission is performed again on a second channel is specifically described, that is: and carrying the identification information of the preset strategy in a response data packet sent to the second node, wherein the response data packet represents that the first node successfully receives the data packet sent by the second node.
It should be noted that the second node and the first node can react in a consistent manner by embedding information representing the policy in the transmitted reply packet.
Specifically, as shown in fig. 7, the ACK packet may be sent at an adjusted time, which is easy to implement and meets the standard. It will be appreciated that the reliability of this operation is guaranteed despite the synchronization error between the second node and the first node. Since the sending and receiving of data packets is a uniform synchronization event established between the second node and the first node. Taking the example that the second node starts to listen to the ACK after sending 600 μ s of the packet and the first node sends the ACK after receiving 1080 μ s of the data packet, the first node may advance the ACK by 320 μ s to represent a strategy for handling internal interference and delay the ACK by 320 μ s to represent a strategy for handling external interference, thereby enabling the second node to recognize the strategies accordingly by checking the reception time of the ACK. Accordingly, if the ACK is not shifted, the second node and the first node will keep data transmission in the current mesh, thereby achieving that the second node and the first node agree on the selected policy to react to interference.
Further, for different interferences, different prediction strategies should be applied to perform interference processing, and based on this, in another embodiment of the present invention, before transmitting identification information of a preset strategy for processing the existing interference while performing the data transmission, it is further required to determine a type of the existing interference;
and determining the identification information of the preset strategy corresponding to the existing interference based on the corresponding relation between the type of the interference and the identification information of the preset strategy.
It is understood that the interference present in a link is divided into internal interference and external interference, internal interference referring to interference caused by other links within the network; the external interference refers to interference caused by other equipment outside the network, and for different interference types, data transmission is carried out again on the second channel based on different strategies, so that failure caused by the interference again in subsequent data transmission can be avoided.
Based on this, in another embodiment of the present invention, when the type of the existing interference is an internal interference, the preset policy includes: the data transmission is carried out again on the second channel, and the time slot for carrying out the data transmission on the first channel is mapped to a new time slot;
when the type of the existing interference is external interference, the preset strategy comprises: and the data transmission is carried out again on the second channel, and the first channel used for the data transmission in the current time slot is listed in a channel blacklist of the link.
It should be noted that, when dealing with internal interference, because the parameter related to the frequency depends on the first node, the timeslot adjustment is simple and effective, and therefore when it is determined that there is internal interference and the strength of the interference exceeds a preset threshold, the current timeslot is mapped to a new timeslot through a preset strategy, so that data transmission failure caused by the current timeslot still in the next data transmission can be avoided. For the external interference existing in one channel, the time slot adjustment will lose significance because of the persistence of the external interference, so that the first channel subjected to the external interference needs to be put into a blacklist, and the first channel will not be used for data transmission in the subsequent time slot, thereby avoiding the data transmission interference caused by the channel quality.
Further, since the information embedded in the ACK time is very limited, further considerations need to be taken to ensure that the policy is consistently and reasonably enforced by the transceiving node. Specifically, three different situations can be included:
1. no change: for example, when the data transmission fails due to poor link quality but the first node considers that the interference is not serious, the first node notifies the second node to maintain normal data transmission.
2. And (3) synchronous time slot adjustment: when the second node and the first node agree on a slot change policy, they both use an algorithm to map the current slot to a new slot. In practical application, a linear congruence generator can be used, that is, a pseudo-random sequence is generated by using discontinuous piecewise linear equation calculation.
3. Channel black list: when external interference is detected, both the second node and the first node blacklist the last used data channel.
Further, the link may blacklist a certain number of channels of the slotframe, and then de-blacklist. Wherein the number of slotframes used for the blacklist may be decided by considering the number of available data channels, for example: when there is sufficient channel resources, the link may blacklist the channel for a relatively long time, as it does not impair network throughput. Otherwise, the black list should be kept short in order to timely release the channel resources for data transmission.
In one example, RPL protocol is used as network layer protocol, and the anti-interference method of network described in the invention is implemented on Contiki NGAnd evaluated performance on a dense multi-hop network consisting of 20 nRF52840 nodes deployed at a 50m network 2 In the area, the internal interference may cause serious problems of links in the network, then, the JamLab NG is used for generating reproducible Wi-Fi interference and showing how the external interference has negative influence on the network performance, finally, a data packet is generated at each node according to predefined flow load, the data packet with the packet length of 50 bytes is transmitted to the root node along an uplink, and verification shows that in the example, the method provided by the invention is adopted to improve the transmission reliability of the ZigBee device by 2.9 times, reduce the duty ratio of the ZigBee device by 54.3%, and have remarkable anti-interference performance.
The anti-interference method of the network can enable the nodes in the network to passively observe the existence of interference by utilizing fine-grained information contained in the existing data transmission, further realize the existence and the severity of the interference in local inference, and utilize a simple but effective mechanism to enable the first node and the second node of each link to react to the interference under the condition of no extra control flow, namely, the data damaged by the interference is retransmitted in the customized second channel, and the information exchange is realized by changing the transmission time of ACK, further the first node and the second node finally reach the consistency of the reaction strategy of the interference, thereby effectively processing the interference.
Fig. 8 illustrates a physical structure diagram of an electronic device, and as shown in fig. 8, the electronic device may include: a processor (processor) 810, a communication Interface 820, a memory 830 and a communication bus 840, wherein the processor 810, the communication Interface 820 and the memory 830 communicate with each other via the communication bus 840. The processor 810 may invoke logic instructions in the memory 830 to perform a tamper resistant method for a network, the method comprising: after data transmission is carried out on a first channel on a link formed by a first node and a second node in the network, whether interference exists on the link is judged according to data information, and the data information is obtained after the data transmission is carried out on the first node and the second node; and when the link has interference, the data transmission is carried out again.
In addition, the logic instructions in the memory 830 may be implemented in software functional units and stored in a computer readable storage medium when the logic instructions are sold or used as independent products. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk, and various media capable of storing program codes.
In another aspect, the present invention also provides a computer program product, the computer program product including a computer program, the computer program being storable on a non-transitory computer readable storage medium, wherein when the computer program is executed by a processor, the computer is capable of executing the interference rejection method for a network provided by the above methods, the method including: after data transmission is carried out on a first channel on a link formed by a first node and a second node in the network, whether interference exists on the link is judged according to data information, and the data information is obtained after the data transmission is carried out on the first node and the second node; and when the link has interference, the data transmission is carried out again.
In yet another aspect, the present invention also provides a non-transitory computer-readable storage medium, on which a computer program is stored, the computer program, when executed by a processor, implementing the method for resisting interference of a network provided by the above methods, the method including: after data transmission is carried out on a first channel on a link formed by a first node and a second node in the network, whether interference exists on the link is judged according to data information, and the data information is obtained after the data transmission is carried out on the first node and the second node; and when the link has interference, the data transmission is carried out again.
The above-described embodiments of the apparatus are merely illustrative, and the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one position, or may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware. With this understanding in mind, the above-described technical solutions may be embodied in the form of a software product, which can be stored in a computer-readable storage medium such as ROM/RAM, magnetic disk, optical disk, etc., and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the methods described in the embodiments or some parts of the embodiments.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (7)
1. An interference rejection method for a network, applied in a first node of the network, the method comprising:
determining a time slot, a first channel and a second channel for data transmission, wherein the time slot, the first channel and the second channel are determined based on an autonomous scheduling protocol, and the second channel is a spare channel of the first channel;
after data transmission is carried out on the basis of the first channel on a link formed by a first node and a second node in the network, whether interference exists on the link is judged according to data information, and the data information is obtained after the data transmission is carried out on the first node and the second node;
when the link has interference, utilizing the second channel of the link to perform data transmission again;
performing weighted calculation according to the estimated probability of the link interference occurring in the previous time slot to obtain the estimated probability of the link interference occurring in the current time slot;
determining the interference strength of the link when the link is interfered according to whether the estimated probability of the current time slot exceeds the preset probability;
when the interference strength exceeds a predefined threshold, the data transmission is performed again on the second channel, and the identification information of the preset strategy for processing the existing interference is transmitted while the data transmission is performed, so that the second node processes the existing interference together with the first node according to the preset strategy identified by the identification information of the preset strategy, and the initial value of the estimation probability is set based on the traffic load of the network.
2. The method of claim 1, wherein the data information comprises a data packet received by the first node;
the determining whether there is interference on the link according to the data information specifically includes:
judging whether the received data packet is a correct data packet from the second node on the link;
determining that interference exists on the link in response to the received data packet not being the correct data packet.
3. The method of claim 2, wherein said determining whether the received packet is a correct packet from the second node on the link comprises:
determining that the received data packet is not the correct data packet in response to the received data packet satisfying at least one condition of a preset set of conditions;
wherein the preset condition set comprises the following conditions:
the received data packets are data packets of other links in the network;
the data packets received in two adjacent time slots are the same data packet;
the received data packet is an invalid data packet which cannot be analyzed, and the average value of all received signal intensities collected in a preset time length exceeds a preset intensity threshold value.
4. The method according to claim 1, wherein said transmitting, while said data transmission is being performed, identification information of a preset policy for handling said existing interference comprises:
and carrying the identification information of the preset strategy in a response data packet sent to the second node, wherein the response data packet represents that the first node successfully receives the data packet sent by the second node.
5. The method according to claim 1, wherein said transmitting, while performing said data transmission, identification information of a preset policy for handling said existing interference further comprises:
determining a type of the interference present;
and determining the identification information of the preset strategy corresponding to the existing interference based on the corresponding relation between the type of the interference and the identification information of the preset strategy.
6. The method according to claim 5, wherein, when the type of the existing interference is internal interference, the preset policy includes: the data transmission is carried out again on the second channel, and the time slot for carrying out the data transmission on the first channel is mapped to a new time slot;
when the type of the existing interference is external interference, the preset strategy comprises: and the data transmission is carried out again on the second channel, and the first channel used for the data transmission in the current time slot is listed in a channel blacklist of the link.
7. An electronic device comprising a memory, a processor and a computer program stored on said memory and executable on said processor, characterized in that said processor, when executing said program, implements the steps of the tamper-resistant method of the network according to any one of claims 1 to 6.
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